1. Field
Exemplary embodiments of the present invention relate to semiconductor design technology, and more particularly, to a semiconductor device including a data output circuit to support a pre-emphasis operation.
2. Description of the Related Art
FIG. 7 is a block diagram of a conventional data output circuit.
Referring to FIG. 7, the conventional data output circuit includes a pre-main driving unit 700 and a main driving unit 720.
The pre-main driving unit 700 is configured to invert and drive output data OUT_DATA.
The main driving unit 720 is configured to drive output data of the pre-main driving unit 700 to a data output pad DQ.
As such, the conventional data output circuit simply drives the output data OUT_DATA to the data output pad DQ without a pre-emphasis operation. Therefore, the data output circuit outputs a different swing amplitude of voltage depending on the pattern of the output data OUT_DATA, as indicated in a voltage level waveform of the data output pad DQ of FIGS. 6A and 6B (PRIOR ART).
That is, during a period A or C where the output data OUT_DATA rapidly changes between the patterns ‘0’ and ‘1’, the voltage level of the data output pad DQ swings between a voltage level lower than a power supply voltage VDD by a certain amount and a voltage level higher than a ground voltage VSS by a certain amount. However, during a period B where the pattern ‘0’ or ‘1’ of the output data OUT_DATA is maintained for a certain time or more, the voltage level of the data output pad DQ swings between the power supply voltage VDD and the ground voltage VSS.
As such, the swing amplitude of the conventional data output circuit may be irregularly varied depending on the pattern of the output data OUT_DATA. Accordingly, jitter characteristics may be degraded by an inter-symbol interference (ISI) effect in a data output channel.